Quick Notes

Python

Easy & beginner-friendly
Used in AI, ML, Data Science
No need to declare data types
Example: print("Hello")

Go (Golang)

Beginner Level:
- Definition: Go (Golang) is an open-source programming language developed by Google. It is designed for simplicity, performance, and efficient concurrency.
- Key Features:
  - Compiled language (fast execution)
  - Simple and clean syntax
  - Built-in concurrency support
- Basic Structure:
```
package main

import "fmt"

func main() {
    fmt.Println("Hello World")
}
          
```
- Variables:
```
var name string = "Go"
age := 20   // short declaration

fmt.Println(name, age)
          
```
- Data Types: int, float64, string, bool

Intermediate Level:

Functions:


func add(a int, b int) int {
    return a + b
}

result := add(5, 3)
fmt.Println(result)

Arrays & Slices:


// Array
var arr [3]int = [3]int{1, 2, 3}

// Slice (dynamic)
slice := []int{1, 2, 3, 4}
slice = append(slice, 5)

fmt.Println(slice)

Loops:


for i := 0; i < 5; i++ {
    fmt.Println(i)
}

Conditionals:


x := 10

if x > 5 {
    fmt.Println("Greater")
} else {
    fmt.Println("Smaller")
}

Advanced Level:

Structs (like classes):


type Person struct {
    name string
    age  int
}

p := Person{name: "John", age: 25}
fmt.Println(p.name)

Concurrency (Goroutines):


func printMsg() {
    fmt.Println("Hello from Goroutine")
}

go printMsg()

fmt.Println("Main Function")

Channels:


ch := make(chan string)

go func() {
    ch <- "Hello"
}()

msg := <-ch
fmt.Println(msg)

Error Handling:


func divide(a, b int) (int, error) {
    if b == 0 {
        return 0, fmt.Errorf("cannot divide by zero")
    }
    return a / b, nil
}

Real-World Uses:
- Backend development (APIs, servers)
- Cloud systems (Docker, Kubernetes)
- Microservices architecture
- DevOps tools

Ruby

Simple & readable syntax
Used in web development
Popular framework: Rails
Example: puts "Hello"

Programming Language Notes

Java

Beginner Level:
- Definition: Java is a high-level, object-oriented programming language used to build platform-independent applications.
- Basic Syntax: Java programs are written inside classes and executed using the main method.
- Example: System.out.println("Hello World");
- Key Concepts: Variables, Data Types (int, float, char), Operators
Intermediate Level:
- OOP Concepts: Class, Object, Inheritance, Polymorphism, Encapsulation, Abstraction
- Collections Framework: ArrayList, HashMap, HashSet
- Exception Handling: try, catch, finally, throw
- Multithreading: Running multiple threads simultaneously
Advanced Level:
- JVM Architecture: ClassLoader, Memory Areas, Execution Engine
- Spring Framework: Used for enterprise applications
- Hibernate: ORM tool for database interaction
- Microservices: Building scalable distributed systems
Uses: Android apps, enterprise software, backend systems

JavaScript

Beginner Level:
- Definition: JavaScript is a scripting language used to create interactive web pages.
- Basic Syntax: Runs inside browser
- Example: console.log("Hello World");
- Core Concepts: Variables (let, const), Functions, Loops
Intermediate Level:
- DOM Manipulation: Changing HTML/CSS using JS
- Events: onclick, onsubmit, keypress
- ES6 Features: Arrow functions, template literals, destructuring
- Asynchronous JS: Callbacks, Promises, async/await
Advanced Level:
- Closures: Functions remembering their scope
- Event Loop: Handles async execution
- Frameworks: React, Angular, Vue
- Backend: Node.js for server-side development
Uses: Web apps, APIs, full-stack development

Python

Beginner Level:
- Definition: Python is a high-level, easy-to-learn programming language.
- Syntax: Simple and readable
- Example: print("Hello World")
- Basics: Variables, Lists, Tuples, Dictionaries
Intermediate Level:
- Functions: def keyword
- OOP: Classes and objects
- Modules: Importing libraries
- File Handling: Reading and writing files
Advanced Level:
- Libraries: NumPy, Pandas, Matplotlib
- Machine Learning: Scikit-learn, TensorFlow
- Web Frameworks: Django, Flask
- Automation: Scripts for tasks
Uses: AI, data science, automation, web apps